1. Technical Field
The present invention relates to a biological sample reaction chip, a biological sample reaction apparatus and a biological sample reaction method, which are intended for the purpose of carrying out biological sample reactions such as nucleic acid amplification.
2. Related Art
Methods for carrying out chemical analysis, chemical synthesis or bio-related analysis using microfluidic chips in which microchannels are provided on a glass substrate or the like have been attracting attention. Microfluidic chips, also known as μ-TAS (micro-Total Analytical System) or Lab-on-a-chip, provide a number of advantages over devices of the related art. For example, the sample and reagent amounts required are small, the reaction time is short, and the amount of waste generated is small. Such advantages offer promise for the use of these devices in a broad range of fields, including medical diagnostics, on-site environmental and food analysis, and the manufacture of pharmaceuticals and chemical products. Because the amount of reagent used is small, the cost of tests can be lowered. Moreover, the small amounts of sample and reagent used enable the reaction time to be considerably shortened, resulting in greater test efficiency. When such devices are used for medical diagnosis in particular, the smaller size of specimens such as blood collected for use as the sample has the added advantage of being less onerous to the patient.
The polymerase chain reaction (PCR) is familiar as a method of amplifying genes such as DNA or RNA used as reagents or samples. The PCR method is carried out by placing a mixture of the target DNA and reagent in a tube and, within a temperature control device known as a thermal cycler, effecting a reaction by repeatedly varying the temperature between three levels, that is, 55° C., 72° C. and 94° C. in cycles of several minutes each. It is possible in this way, through the action of the enzyme known as polymerase, to amplify only the target DNA about two-fold per temperature cycle.
In recent years, a process known as real-time PCR which employs a special fluorescent probe has come into practical use, making it possible for the DNA to be quantitatively determined as the reaction is being carried out. Real-time PCR is widely used in research and clinical tests on account of its sensitivity of measurement and high reliability.
However, in an apparatus of the related art, the amount of reaction fluid required for the PCR is typically several tens of microliters, and it is basically possible to measure only one gene in a single reaction system. Although there does exist a method in which a plurality of fluorescent probes are inserted and, by distinguishing between the colors thereof, about four types of genes are simultaneously measured, the only way to measure more genes than this at the same time has been to increase the number of reaction systems. Because the amount of DNA extracted from a specimen is generally small and the reagents are expensive, carrying out measurement simultaneously in a large number of reaction systems has been difficult.
JP-A-2006-126010 and JP-A-2006-126011 disclose inventions in which, using a rotationally driven apparatus, PCR reaction solutions and samples of liquid specimens such as blood are accurately delivered to a plurality of chambers.
JP-A-2000-236876 discloses a method in which an array of microwells is created on a semiconductor substrate and PCR reactions are carried out within the wells, thereby using very small sample quantities to amplify a large number of DNA samples at the same time and carry out analysis.